A ring radius R having a linear charge density $\lambda$ moves towards a solid imaginary sphere of radius $\frac{R}{2}$,  so that centre of the ring passes through the centre of the sphere. The axis of the ring perpendicular to the line joining the centers of the ring and sphere. The maximum flux through the sphere in this process is  $\frac{\lambda \pi R}{n{\epsilon }_0}$. Then the value of n=